1. Field of the Invention
The present invention relates to a clamp for holding one or more transmission cables.
2. Description of the Background Art
FIGS. 1 and 2 illustrate a grounding clamp 1, in accordance with the background art. The grounding clamp 1 physically and electrically interacts with a plurality of shielded cables 2 and an electrically grounded chassis 3 of a piece of electrical equipment. The purpose of the grounding clamp 1 is to equate the ground levels of the shielded cables 2 to the ground level of the grounded chassis 3, in order to reduce the likelihood of electrical noise. The grounding clamp 1 also serves to provide strain relief to electrical connections made between the conductors 4, within the shielded cables 2, and terminals, within the electrical equipment. Further, the grounding clamp 1 acts to organize the shielded cables 2, so that the shielded cables 2 are directed in a set direction and are not free to move about.
The physical and electrical interaction of the grounding clamp 1 and the grounded chassis 3 will now be described. The grounding clamp 1 is in the form of a hose clamp, having an engagement ring 5, and being constructed of an electrically conductive material. A hole is drilled in the engagement ring 5 and a threaded fastener 6 is passed through the hole. The threaded fastener 6 is screwed into the grounded chassis 3 thereby establishing electrical conductivity between the grounding clamp 1 and the grounded chassis 3.
The physical and electrical interaction of the grounding clamp 1 and the shielded cables 2 will now be described. An insulation layer 7 is removed from each of the shielded cables 2 to exposes a shielding layer 8. The exposed shielding layers 8 of the shielded cables 2 are aligned so that the hose clamp's engagement ring 5 will overlie the shielding layers 8. The grounding clamp 1 is tightened, via a tightening screw 9, and electrical conductivity is thereby established between the shielding layers 8 and the grounding clamp 1. Therefore, electrical conductivity is also established between the shielding layers 8 and the grounded chassis 3.
The background art's grounding clamp 1 suffers several drawbacks. First, under-tightening of the tightening screw 9 can lead to play between the shielding layers 8 and result in noisy grounding. Conversely, over-tightening of the tightening screw 9 can lead to tearing of one or more of the shielding layers 8 against sharp edges of the grounding clamp 1, such as a head of the threaded fastener 6 or edges of the engagement ring 5. Therefore, it is up to the skill and/or experience of the installer to determine the torque needed, and/or the installer must resort to using a torque wrench.
A second drawback of the background art's hose clamp is that the number of shielded cables 2 to be connected to the grounded chassis 3 can vary between applications. Therefore, if a single hose clamp size is used, it must have an engagement ring 5 of sufficient size to accommodate the maximum number of shielded cables 2. When fewer than the maximum number of shielded cables 2 are installed, the installer must spend assembly time excessively turning the tightening screw 9 to downsize the engagement ring 5 to accommodate the fewer shielded cables 2. Alternatively, a varied supply of hose clamps must be keep on hand by the installer so that the size of the hose clamp can be selected in accordance with the number of shielded cables 2 to be installed.
A third drawback of the background art's hose clamp is its unsightly, unprofessional appearance. The hose clamp literally squeezes all of the shielded cables 2 into a bundle. The shielded cables 2 overlay each other in random disarray. The electrical equipment associated with the grounded chassis 3 can sometimes cost thousands of dollars. A simple hose clamp may not instill confidence in the owners and operators of the costly equipment, that competent and reliable components have been used in the construction of the electrical equipment.
Therefore, there exists a need in the art for a grounding clamp, which automatically applies uniform compression to all of the shielding layers 8 of the shielded cables 2, thus simplifying the installer's responsibilities, and thus protecting the shielding layers 8 from damage. Also, there is a need for a single sized grounding clamp which can accommodate various numbers of shielded cables 2. And further, there exists a need in the art for a grounding clamp which provides a neat and orderly arrangement of the shielded cables 2.